Tony Palmer: he's with the band

They were music megastars, and they all opened up to him. As Tony Palmer's best films resurface, the documentarian talks to Phelim O'Neill about Leonard Cohen's tears, John Lennon's fake beard – and the day Liberace invited him into his hot tub

Tony Palmer was studying moral sciences at Cambridge University in the 1960s when a moderately famous band arrived in town. "I got a call to attend this press conference the Beatles were holding, to cover it for the college paper," he recalls. "They'd had a No 1 single or two by then, so they were very well known – but not yet intergalactic. Afterwards, John Lennon came up and asked me why I hadn't asked them any questions. I told him I found the whole thing pretty silly. He laughed, and when I told him I was studying moral sciences, he thought me pretty silly, too. He wanted someone to show him around the university – I realised much later that he was very interested in education. So we meet up later and he's in disguise – a dreadful one, with a large fedora hat, long brown raincoat and fake beard. There were no screaming fans following him on campus. I got him into places like the Wren library, which he enjoyed. I got the feeling he was interested in getting an education, a formal one which he never did get."

This is how Palmer, now in his 70s, talks: in perfectly paced anecdotes, full of colour, character, drama, insight, action – and of course stars, generally the biggest stars of all. The same could be said of his acclaimed music documentaries, four of which have just been released on DVD. Their subjects are Liberace, Leonard Cohen, Frank Zappa and the Beatles. As he is enjoying explaining, it was the Fab Four, and Lennon in particular, who set him on a path that would lead to over 100 films about everyone from Maria Callas to Igor Stravinsky.

Lennon gave Palmer his number, saying if he was ever in London to call so he could return the favour. But Palmer had no intention of even visiting the city. "I was going to be an academic," he says. Nevertheless, two years later, he ended up there, working for the BBC. "I'd worked with Ken Russell on his Isadora Duncan film and Jonathan Miller on Alice in Wonderland. My first film was on Benjamin Britten, and it was the first British documentary to be networked across America. This was seen as some success, but I don't think it was much down to the quality of the film."

It got him noticed, and he quickly rose through the BBC ranks, allowed more freedom than a newcomer could normally expect. When he finally met up with Lennon again (who by then was "intergalactic"), the Beatle told him what he must do. "There were all these great bands around, Jimi Hendrix, Pink Floyd, and they weren't getting any serious coverage. You could do Top of the Pops or Juke Box Jury – that was it. People like Hendrix didn't want to do those. John told me it was my duty to get them on to television. I wasn't much into that type of music then, but anyone could see how incredible Hendrix was. Television was just ignoring these people. I said, 'John what can I do? I'm new at the BBC and I don't have an "in" with any of these bands.' He said, 'I'll provide the introductions, you can do everything else.'"

So Lennon went through his contacts, and Palmer dealt with the artists directly, filming Hendrix, Eric Burdon (of the Animals), Cream, Frank Zappa and Pete Townshend, gaining the sort of access that could only be dreamt of today. Lennon also provided the title for Palmer's examination of politics and rock'n'roll – All My Loving – as well as "darkly hinting that the Rolling Stones mustn't be included. Mick Jagger has never forgiven me for that."

It took a while for All My Loving to be broadcast. David Attenborough, then BBC2 controller, vowed it would air over his dead body, says Palmer. When it finally did reach the living rooms of Britain, its impact was seismic. "David Jacobs [Juke Box Jury's presenter] came up to me at a BBC party and very angrily poked me in the chest, saying I'd ruined his career. Within about three weeks of All My Loving being aired, Juke Box Jury was cancelled. They'd seen the writing on the wall."

Ringo Starr as Frank Zappa in 200 Motels

At the start of the 1970s, having left the BBC, Palmer made the surreal film Frank Zappa's 200 Motels. He was seen as a safe pair of hands, one of the few people capable of making something watchable out of Zappa's script about him and his band going crazy in a small town. The script, Palmer recalls, was in a state. "He dragged in this huge trunk full of scraps of paper, stacks of them, plus notes and drawings. I said to him, 'I see what you're trying to do, to show the effects of a drug trip. We can do this, but not on the budget we have.'"

Zappa's ideas for trippy visuals would have been too expensive and time-consuming to realise, since movie-style special effects required specialist equipment. So Palmer had a brainwave: shoot on videotape, which had steadily improved since its invention in the 1950s, reaching the point where it could conceivably handle being blown up to cinema-sized screens. "I met with whoever was in charge of MGM that month, and I remember him slowly putting his teacup down on his desk when I told him my plan, saying, 'What's videotape?'"

Palmer's experiment didn't just work – it was cheaper, and the results could be transferred back to film for conventional editing. A bizarre, anything-goes mix of druggy interludes, hippy slang, animation, music and counter-culture humour, 200 Motels proved a hit on the midnight-movie circuit, with the part of Zappa played by Ringo Starr, thinly disguised in beard and wig.

By the time he made Bird on a Wire, his 1972 film about Leonard Cohen on tour in Europe, Palmer was feeling bullish. "I told them I wanted total access, no door closed." He was in luck. "It seemed Cohen was going to retire after the tour, the record company wasn't interested, so there were no company people around. It was just the band and our little film crew in the dressing room."

Bird on a Wire

The result is a spellbindingly intimate portrait: Cohen comes across as supremely focused, polite and gentle, not to mention exhausted. It culminates in a gig in Tel Aviv. The audience, trying to get closer to the stage, are roughly handled by the plentiful security as Cohen softly and firmly calls for calm. "Cohen singing Bird on a Wire at that gig, tears streaming down his face – that's the man." For the live portions of this mesmerising work (which Palmer recently recut, fixing all the tampering that occurred after it left his hands), the camera is fixed tightly on Cohen. The band, the venue and the rest of the world fade away.

When we move on to La Divina, his 1987 Maria Callas documentary, Palmer offers an insight into his approach. "Rather than show her as an opera-singer who is a fragile, damaged woman in deep trouble, I presented her as a fragile, damaged woman in deep trouble who is also an opera singer." Another thing that marks out his documentaries is the lack of voiceover. "Oh, I hate it when they try to tell you what to think," he says. My epiphany came with 2001: A Space Odyssey. The beginning of the film, the apes, all tells a story without words, just the music. I left the cinema invigorated and desperate to get back to editing."

I wonder what Palmer thinks of Behind the Candelabra, Steven Soderbergh's new film about Liberace. "It's a great movie, and Michael Douglas gives a career-best performance. But that's not Liberace. Everyone knew he was gay, but he never minced like that. He'd walk across a room like anyone else. He'd look you dead in the eye. He was straight as a die." Palmer pauses. "He was incredibly generous, though – they got that right. I remember we were shooting him around his swirl bath. He offered to let us use it. I thought it a bit much, and he admitted he never used it himself – yet there are entire scenes set in that bath in the movie." What they failed to capture, he adds, was the man's excessive wealth. "Soderbergh certainly didn't have the budget for that."

Most of Palmer's films were made for TV, something he believes would be unworkable today. "In those days, you were dealing with one or two BBC people. They'd defend you, stick up for you if you made a mistake as long as you were honest about it. They'd trust you to go off and make your films unsupervised. Today, it's all committee-run, TV and music. I think [director general] Tony Hall is the best thing to happen to the BBC in decades. I wrote to him after they sacked 500 people telling him he should sack more."

Years ago, Ken Russell called Palmer. "He asked me if I could remember who was in charge of production at the BBC in the autumn of 1971. I told him, 'Frankly, Ken, I can't remember nor do I really care.' 'Exactly!' he boomed. 'They're all gone and forgotten and we're still making films.'"

Indeed they are. There's Palmer's forthcoming and long-gestated film about Vangelis. And he's currently arranging screenings of Nocturne, a documentary about Benjamin Britten made for the composer's centenary year. Naturally, this being Palmer, these aren't your run-of-the-mill screenings: one will take place in the White House. The plan was to show it in November, on what would have been Britten's 100th birthday, but the date was shifted. "That's not actually on his birthday, I told them. But they said it's the only day Mrs Obama is free to attend."

• Leonard Cohen: Bird on a Wire, Frank Zappa's 200 Motels, All You Need is Love: The Beatles, and The World of Liberace are out now.